Our primary objective is to obtain experimental values of the Zimm-Bragg growth and nucleation parameters, s and sigma, for each of the 20 naturally occurring amino acids. These parameters will characterize, in a quantitative way, the tendency of each amino acid residue in a protein to adopt an alpha-helical or a coil conformation. These experimental values of s and sigma will then be used to analyze the conformational properties of proteins. The parameters themselves will be obtained by studying the helix-coil transition of random copolymers of two types of amino acid, a host (whose s and sigma values are known) and a guest (whose s and sigma values are to be determined). Random copolymers of varying chain length and of varying composition of the host and guest residues will be synthesized and fractionated; melting data will be obtained for these fractions. Appropriate theory is now available for analyzing such experimental data.